Galileo Encounters Earth

On the Cover: How might our own planet appear to an alien spacecraft sweeping by? This mosaic of images taken by Galileo gives us some idea. Here the snow and ice of Antarctica, surrounded by oceans of liquid water, tell much about the unique nature of this watery planet in our solar system. But could an alien detect signs of life? Not in these images, where features smaller than 5 kilometers (3 miles) are not visible. But a spacecraft like Galileo carries many types of instruments, and some of these did detect evidence of life.JPL / NASA

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4 The Future of the U.S. Space Program: Norman Augustine reports on the findings of the National Space Council's Advisory Committee on the Future of the U.S. Space Program.